Height limiter



July 21, 1964 P. F. MCADAMS HEIGHT LIMITER 5 Sheets-Sheet 1 Filed April 12 1962 INVENTOR PAUL F. M ADAMS ATTORNEY July 21, 1964 P. F. M ADAMS 3,141,562

HEIGHT LIMITER' Filed April 12, 1962 5 Sheets-Sheet 2 FIG. 2

INVENTOR PAUL F. M ADAMS ATTO R N EY July 21, 1964 p MCADAMS 3,141,562

' HEIGHT LIMITER Filed April 12, 1962 5 Sheets-Sheet 3 FIG. 3

INVENTOR 3 PAUL F. M ADAMS 66 ATTORNEY July 21, 1964 p McADAMs HEIGHT LIMITER Filed April 12, 1962 5 Sheets-Sheet 4 INVENTOR PAUL F. M ADAMS 3am cz/Jr ATTORNEY y 21, 1954 P. F. MOADAMS 3,

HEIGHT LIMITER Filed April 12, 1962 5 Sheets-Sheet 5' FIG. 5

INVENTOR PAUL F. M ADAMS W Zdf ATTORNEY United States Patent 3,141,562 HEIGHT LIMITER Paul F. McAdams, St. Joseph, Mich, assignor to Clark Equipment Company, a corporation of Michigan Filed Apr. 12, 1962, Ser. No. 186,957 4 Claims. (Cl. 214-140) This invention relates to vehicles which carry a material handling implement at the outer end of a pivoted boom arm or arms, and more particularly to a mechanism for automatically limiting the height to which the implement can be raised under certain circumstances.

While the invention is described and illustrated herein as applied to a tractor shovel which has a material handling bucket carried at the outer ends of forwardly projecting boom arms, it will be appreciated that the invention is not limited to such vehicles and may be applied with equal facility to other equivalent vehicles as well.

In the operation of material handling vehicles such as tractor shovels and tractor loaders, for example, it is sometimes desirable to limit the height to which the bucket or other implement can be raised. As an illustration, such vehicles frequently are operated inside railroad cars or inside buildings; and if the vehicle provides a maximum potential height for the bucket which is higher than the ceiling or roof of the enclosure in which the vehicle is operating, it is desirable to limit the height to which the bucket can be raised in order to prevent the bucket or the load therein from accidently contacting the ceiling or roof. Another example involves the use of tractor loaders to load dump trucks. If the tractor loader has the capability of elevating the bucket to a height considerably greater than is actually required to clear the upper margins of the dump bodies into which the material is to be deposited, efficiency will be promoted if it is possible readily to limit the height to which the bucket is raised. If the bucket elevating mechanism is adjusted so that the bucket raises only to the height which is actually required to clear the edges of the dump body time will be saved during each cycle for elevating the bucket and also lowering it again after dumping has been accomplished.

The object of the present invention is to provide a mechanism for limiting the height of the bucket, fork or other implement to a predetermined amount.

A further object is to provide means for the operator readily to adjust the maximum height from his operators station on the vehicle.

In carrying out my invention in one form I provide a support secured to the vehicle near the operators station. A pivotal member is pivotally connected to this support for pivotal movement about a horizontally disposed axis. A vertically disposed link is connected between the pivotal member and the forwardly projecting boom arm of a tractor shovel. A horizontally disposed cam follower member is pivotally connected to the pivotal member. An adjustable cam actuator member is arranged to be engaged by the cam follower member, and this actuator member is located and adapted for ready adjustment by the operator. A pump device is arranged to be operated by the cam follower member upon predetermined movement thereof, and means are provided responsive to the operation of the pump device for cutting off the flow of fluid to the hydraulic actuating means for the boom arm to stop raising movement thereof.

The above and other objects, features and advantages of the invention will become apparent to those familiar with vehicles of this type from the following disclosure of a preferred embodiment of the invention taken together with the accompanying drawing in which:

FIGURE 1 is a partial side elevational view of a tractor shovel vehicle embodying the present invention.

3,141,562 Patented July 21, 1964 FIGURE 2 is an enlarged view of a mechanism which is included in the vehicle of FIG. 1 adjacent the operators station thereon,

FIGURE 3 shows the mechanism of FIG. 2 in a different operating position,

FIGURE 4 shows a hydraulic device which is utilized as an element of this invention,

FIGURE 5 is an enlarged view of the outside of a valve mechanism which is utilized for controlling the raising and lowering operation of the boom arms on the vehicle and for other functions,

FIGURE 6 is an enlarged sectional view of a portion of the valve mechanism of FIG. 5, and

FIGURE 7 shows the structure of FIG. 6 in another operating position.

Referring to FIG. 1 of the drawing, there is shown a portion of a tractor shovel vehicle which is indicated generally by the numeral 10. The rear portion of the vehicle is omitted inasmuch as it is not required to illusrate the present invention. The vehicle 10 includes a body portion 12 which is supported on a main frame portion 14 which in turn is carried by front wheels 16 and rear wheels 18, only one each of the front and rear wheels being visible in this illustration. The vehicle 10 also includes an operators station indicated generally by the numeral 20 which includes a seat 22, an operators steering wheel 24 and control levers 26, 28 and 30.

The vehicle It also includes a pair of boom arms 32 which have a slight downwardly bent configuration as illustrated. Only one of these is visible in FIG. 1, but it wili be readily understood that there is another boom arm on the other side of the machine and the two are located symmetrically with respect to a center plane through the vehicle body. Each boom arm has its rearward end pivotally mounted at 34 on the body of the vehicle while its forward end has pivotally connected thereto at location 36 a yoke member 38. Also connected between the vehicle body and yoke 33 on each side of the machine is a stabilizing or guide bar 40. Guide bar 40 pivotally is connected at point 42 on a bracket portion d4 projecting upwardly from the main body portion, while the other end of stabilizing bar 40 is connected at 46 to yoke 38. Pivotally mounted on yoke 38 is a bucket 48, the bucket 48 being pivotally movable about a transverse axis at 47 by means of a hydraulic actuator or actuators (not visible) housed within yoke 38.

The main boom arms 32 together with yoke 38, bucket 48 and auxiliary arms 40, are raised by operating hydraulic actuators 52.. The actuators 52 are operated by means of a valve mechanism 53 which is controlled from operators station 20, as described hereinafter. There is an actuator 52 on each side of the vehicle 10 connected to its respective boom arm at location 58. The lower end of actuator 52 is connected at location 54 to a bracket 56 which depends from the main frame portion 14 of the vehicle. The actuators 52 illustrated are the. pistoncylinder type and are extended by admitting hydraulic fluid under pressure to the lower end of the actuators, which causes the piston rod portion 59 to slide out of the cylinder portion of the actuator and raise the boom arms 32. This raises the boom and auxiliary arms, the yoke 38 and the bucket 48.

The bucket 48 of vehicle It may be utilized in the position illustrated in FIG. 1 to obtain a load of bulk material or the like by driving the vehicle forwardly into a pile of the material to be loaded in order to fill the bucket. Or, if desired, this vehicle may be utilized to excavate earth or other hardpacked material by lowering the bucket 48 below the position illustrated in FIG. 1 and then driving the vehicle forwardly in order to force the cutting edge 50 of the bucket into the material to be excavated, and thereby obtain a bucketload of such marterail. After the bucket has been filled sufliciently by excavation or other loading, the load may then be transported by the vehicle and dumped into a truck, hopper or other depository. Upon reaching such point of unloading the bucket is raised sufficiently to dump into the depository, and then the bucket is pivoted by remote control from the operators station from the carrying position to a dumping position to discharge the material from the bucket.

If this vehicle is to dump into a truck which does not require lifting the bucket to the maximum height available, it may be desirable to limit the height to which the boom arms will raise the bucket in order to speed operations. Or, as mentioned previously, it may be desirable to limit the height to which the bucket will raise in order to avoid engaging a ceiling, roof or other structure over the location where dumping is to occur.

There is indicated generally by the numeral 60 in FIG. 1 a portion of a mechanism which is utilized to limit the height to which the boom arms 32 and the bucket carried thereby may be raised. The structure 60 is illustrated in greater detail in FIG. 2 which is an enlarged view of a fragmentary portion of FIG. 1 with the side panel of the vehicle body removed to show the part of the structure which is housed within the body portion. As shown in FIG. 2, the structure 60 includes a support member 62 which is secured in a suitable manner to a base member 64 which in turn is secured to a panel member 66 which forms a portion of the front wall of the operators compartment 20. The support 62 has pivotolly connected thereto at 68 a generally triangular shaped pivotal member 70. The member 70 pivots about horizontally disposed axis 68 responsively to movement of boom arms 32. The boom arm 32 shown is connected to pivotal member 70 by means of a link 72 which is pivotally connected to the boom arm at 74 and at 76 to member 70. Also pivotally connected to the pivotal member 70 at location 77 is a horizontally disposed cam follower member 70 which projects through an opening in panel 64.

On the front of base 64 a cam actuator member 80 is pivotally mounted at 32 on a bracket 84 extending from the base. At the top of cam actuator member 80 it is provided with a roller 36 which engages the oblique bottom surfiace 7 9 of cam follower member 78. The cam actuator 80 is arranged to be moved inwardly and outwardly by means of a screw 83 which is operated by hand wheel 90. Threadedly engaged with the screw 88 is a collar 92 having trunnion portions indicated by the numeral 94 on each side thereof which project into slots 96 in the cam actuator member 80. Thus, as the hand wheel 90 is turned in the desired direction the collar 92 moves inwardly and outwardly on the screw, and the sliding trunnion connections provided by projections 94 and slots 06 causes the upper end of cam actuator 80 likewise to move inwardly and outwardly to adjust the height to which the bucket may be raised, as explained hereinafter.

FIG. 2 shows the lowered position of the boom arm 32 the same as in PEG. 1. FIG. 3 shows an elevated position of boom arm 32, and it will be noted that in this position of the boom arm the link 72 has raised pivotal member 70 to pivot about point 68 and cause cam follower member 7 8 to move to the left. When cam follower 78 has moved sufliciently to the left as shown in PEG. 3 to cause roller 86 to approach the apex 100 on the lower surface of cam follower member 7 8, the resulting upward movement of a follower roller 90 causes a master cylinder 102 to ope erate a slave device. The term master cylinder is used because this device is somewhat analogous to the device commonly referred to as a master cylinder in a conventional hydraulic braking system for automotive vehicles.

FIG. 4 illustrates the detail construction of device 102. It comprises a piston or plunger 150 which operates in a cylinder 152 to expel oil or other liquid through an aperture 154 and thence through a conduit, not shown, to operate a slave or follower device which is illustrated in FIGS. 6 and 7 and described in detail hereinafter. The device 102 includes a reservoir 156 which supplies liquid, which may be conventional hydraulic fluid, through opening 15% to charge the cylinder 152. Spring 160 is the return spring for the plunger 150, while spring 162 above the intervening slidable member 164 limits the pressure output of device 102.

FIG. 5 shows a view approximately along the line 55 of FIG. 1 of valve bank 53 which includes the valve which operates the hydraulic actuators 52. This operation is accomplished by means of a rod 104 which is connected for operation by operators lever 30. Referring to FIG. 5, the rod 104 is connected at location 106 to a valve which is indicated generally by the numeral 107. The valve 107 includes spool 108 which, when it is pulled to the left, opens the valve 107 within the housing 110 which admits fluid to the bottom of the hydraulic actuators 52 to extend them. In the machine illustrated the boom arms and bucket return downwardly by gravity and this is accomplished by moving thevalve spool 103 in the opposite direction from the neutral position illustrated.

At the right end of valve spool 108 as indicated by the housing projection 112 in FIG. 6 the valve 107 is provided with a mechanism which causes the valve spool 10% to return to a neutral position whenever the device or pump 102 is actuated sufficiently in response to upward movement of the boom arm 32. The mechanism within housing projection is illustrated in detail in FIGS. 6 and 7 of the patent drawing.

The inner end of valve spool 108 is shown at the left edge of FIG. 6. Connected to the spool 108 is an auxiliary spool member 114, the auxiliary spool being joined by a universal connection at 116 for movement in either direction with spool 108. Surrounding the connection 116 is a centering spring 118 which is located between a pair of spring seat members 120 and 122. When the valve spool 108 is in the neutral position the seat spring members 120 and 122 respectively abut annular members 124 and 126 positioned within housing 112. Spring seat member 120 has an offset inwardly projecting flange portion 128 which engages a shoulder portion 129 on spool 108, while spring seat member 122 has an offset inwardly projecting flange portion 130 which engages a shoulder portion 131 on auxiliary spool member 114. When spool 108 is moved to the left as illustrated in FIG. 7 of the drawing the seat member 122 compresses spring 118 and tends to restore the spool to neutral. Similarly when spool 108 is moved to the right, member 120 causes spring 118 to compress and likewise tends to restore the spool 108 to neutral.

When the spool 108 is moved to the left as shown in FIG. 7 a spring 132 which is located between a member 134 closing the end of housing 112 and a slidable sleeve member 136 causes the sleeve 136 to move to theleft and force ball detent members 138 into engagement with shoulder portion 140 on auxiliary spool 114 as illustrated in this figure. This causes the valve to remain in the open position, once it is opened, until it is moved again either by the operators actuating lever 30 or by the automatic restoring means to be described'which causes sleeve 136 to move back to the right and allow the ball detents 138 to move away from shoulder portion 140. This latter action occurs when device 102 is operated. The operation of such device forces fluid under pressure into annular space 142, and because of the greater area 144 on the right side of this annular groove as seen in FIG. 6 compared to the smaller area 146 on the left side, a force is produced which causes the sleeve 136 to move to the right. This releases the detent balls 138 and allows the auxiliary spool 114 and the main spool 108 to move back from the position of FIG. 7 to the neutral position of FIG. 6; such movement of the main spool 108 cuts off the flow of pressurized fluid to the actuators 52 and thereby stops the raising action of the bucket 48.

If the operator desires such raising action to be terminated at a higher elevation he needs only to operate screw 83 by means of hand wheel 90 to move cam actuator member 80 to the left. This has the effect of delaying the operation of device N2 until boom arm 32 has been raised to a higher position. If he wishes the height to be limited to a lower elevation he moves cam actuator to the right.

In the embodiment of the invention shown herein the device 102 and space 142 preferably are connected by a closed circuit so that the liquid which is expelled by device 1ti2 to release the detents returns to device 102 when spring 160 causes plunger 1563 again to extend upon the lowering of boom arm 32 and the consequent retraction of member 78.

While I have described and illustrated herein a preferred embodiment of this invention, it will be apparent that modifications may be made. For example it would be possible to substitute for the pressure producing device 102 a valve which would admit fluid under pressure from a separate source of pressurized fluid such as a pump, in order to actuate sleeve 136. It should be understood therefore that I intend to cover by the appended claims all such modifications falling within the true spirit and scope of this invention:

I claim:

1. An implement height limiter for a vehicle having a pivoted boom arm carrying an implement at the outer end thereof and hydraulic means for raising the boom arm, comprising: a support, a pivotal member pivotally connected to the said support for pivotal movement about a horizontally disposed axis, a vertically disposed link connected between the said pivotal member and the boom arm, a horizontally disposed cam follower member pivotally connected to the said pivotal member for generally horizontal movement as the said link is moved in a generally vertical direction by upward movement of the boom arm to pivot the said pivotal member, an adjustable cam actuator member arranged to movably engage the said cam follower member, a device operated by the said cam follower member upon movement of the cam follower member, and means responsive to the operation of the said device for operating the hydraulic means to stop raising movement of the boom arm.

2. A height limiter for a vehicle having a pivoted boom arm and hydraulic means for raising the boom arm comprising, a support, a pivotal member pivotably connected to the said support, a link connected between the said pivotal member and the boom arm for moving the pivotal member in response to movement of the boom arm, a cam follower member pivotally connected to the said pivotal member for movement therewith in response to movement of the boom arm, a cam actuator member arranged movably to engage the said cam follower member, a device operated by the said cam follower member upon movement thereof to a predetermined position, and means responsive to the operation of the said device for causing the hydraulic means to stop raising movement of the boom arm.

3. A bucket height limiter for a tractor vehicle having pivoted boom arms carrying a bucket at the outer ends thereof, hydraulic actuators for raising the boom arms, and a valve for admitting pressurized fluid to the hydraulic actuators, the said height limiter comprising, a support mounted on the vehicle below the boom arm, a pivotal member pivotably connected to the said support for pivotal movement about a horizontally disposed axis, a vertically disposed link connected between the said pivotal member and the boom arm, a horizontally disposed cam follower member pivotally connected to the said pivotal member for generally horizontal movement as the said link moves in a generally vertical direction to pivot the said pivotal member responsively to upward pivotal movement of the boom arms, an adjustable cam actuator member arranged to movably engage a portion of the lower surface of the said cam follower member, a fluid pressure producing device positioned by the said cam follower member and operated thereby upon movement of the cam follower member, means for holding the valve in the operated position when it is actuated to cause raising of the boom arm, and means responsive to operation of the said fluid pressure producing device for restoring the valve to neutral thereby to stop the raising movement of the boom arm at a selected height.

4. A bucket height limiter for a tractor vehicle having a body portion with an operators station thereon, pivoted boom arms pivoted on the body portion near the operators station and carrying a bucket at the outer ends thereof, hydraulic actuators for raising the boom arms, and a valve controlled from the operators station for admitting pressurized fluid to the hydraulic actuators, the said height limiter comprising, a vertically disposed base member mounted on the vehicle adjacent the operators station, a horizontally projecting support bracket on the said base located below one of the boom arms, a pivotal member pivotally connected to the said support bracket for pivotal movement about a horizontally disposed axis, a vertically disposed link connected between the said pivotal member and the said one boom arm, a horizontally disposed cam follower member pivotally connected to the said pivotal member and projecting through the said base member, the said cam follower member moving in a generally hori zontal direction as the said link moves in a generally vertical direction to move the pivotal member responsively to upward pivotal movement of the said one boom arm, the said horizontally disposed cam member having a downwardly disposed oblique surface adjacent the free end thereof, an adjustable cam actuator member pivotally mounted on the said base member and below the said cam follower member and arranged to engage the said oblique surface thereon and raise the cam follower memher as the cam follower member moves horizontally upon upward movement of the said one boom arm, means for moving the said cam actuator member inwardly and outwardly to adjust the relative horizontal position at which the said cam follower member is moved upwardly above a predetermined height, a plunger and cylinder type fluid pressure-producing device located above the said cam follower and arranged so that the vertical component of the movement of the cam follower member forces the plunger into the cylinder to discharge fluid therefrom, ball detent means for holding the valve in the actuated position when it is actuated to cause raising of the boom arms, and means utilizing the fluid discharged by the said fluid pressure-producing device for releasing the said ball detents and restoring the valve to neutral whereby raising of the boom arm stops at a selected height.

References Cited in the file of this patent UNITED STATES PATENTS 2,030,529 Nash Feb. 11, 1936 2,529,193 Rueter Nov. 7, 1950 2,840,244 Thomas June 24, 1958 3,035,710 Pohl May 22, 1962 FOREIGN PATENTS 1,113,545 Germany Sept. 7, 1961 1,224,436 France Feb. 8, 1960 

1. AN IMPLEMENT HEIGHT LIMITER FOR A VEHICLE HAVING A PIVOTED BOOM ARM CARRYING AN IMPLEMENT AT THE OUTER END THEREOF AND HYDRAULIC MEANS FOR RAISING THE BOOM ARM, COMPRISING: A SUPPORT, A PIVOTAL MEMBER PIVOTALLY CONNECTED TO THE SAID SUPPORT FOR PIVOTAL MOVEMENT ABOUT A HORIZONTALLY DISPOSED AXIS, A VERTICALLY DISPOSED LINK CONNECTED BETWEEN THE SAID PIVOTAL MEMBER AND THE BOOM ARM, A HORIZONTALLY DISPOSED CAM FOLLOWER MEMBER PIVOTALLY CONNECTED TO THE SAID PIVOTAL MEMBER FOR GENERALLY HORIZONTAL MOVEMENT AS THE SAID LINK IS MOVED IN A GENERALLY VERTICAL DIRECTION BY UPWARD MOVEMENT OF THE BOOM ARM TO PIVOT THE SAID PIVOTAL MEMBER, AN ADJUSTABLE CAM ACTUATOR MEMBER ARRANGED TO MOVABLY ENGAGE THE SAID CAM FOLLOWER MEMBER, A DEVICE OPERATED BY THE SAID CAM FOLLOWER MEMBER UPON MOVEMENT OF THE CAM FOLLOWER MEMBER, AND MEANS RESPONSIVE TO THE OPERATION OF THE SAID DEVICE FOR OPERATING THE HYDRAULIC MEANS TO STOP RAISING MOVEMENT OF THE BOOM ARM. 